Light emitting device

ABSTRACT

Disclosed is a light emitting device which includes organic electroluminescent sections each including a first electrode layer, an organic light emitting layer, a second electrode layer and a reflective layer in this order, and a light extraction surface. The reflective layer includes two reflective interfaces. In each of the organic electroluminescent sections, a microcavity structure is formed by a structure including a first reflective interface, a second reflective interface, and the two reflective interfaces. The organic electroluminescent sections include first organic electroluminescent sections and second organic electroluminescent sections. The microcavity structure is configured in such a manner that the first reflective interface and the second reflective interface intensify the light in the first wavelength band and the light in the second wavelength band, and that the two reflective interfaces weaken the light in the first wavelength band and intensify the light in the second wavelength band.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Priority PatentApplication No. 2018-102520 filed on May 29, 2018 and also claims thebenefit of Japanese Priority Patent Application No. 2019-076571 filed onApr. 12, 2019, the entire contents of which are incorporated herein byreference.

BACKGROUND

The present disclosure relates to a light emitting device using organicelectroluminescent sections that emit light by an organicelectroluminescence (EL) phenomenon.

In recent years, a large number of proposals have been made in regard ofthe structure of a light emitting device using organic EL elements (see,for example, WO 01/039554, JP 2006-244713A, JP 2011-159431A, and JP2011-159433A).

SUMMARY

Among such light emitting devices, those of the top emission system havea problem that attendant on enlargement in size, it has become difficultto realize both good feed performance and good viewing anglecharacteristic of chromaticity. Therefore, it is desirable to provide alight emitting device in which both good feed performance and goodviewing angle characteristic of chromaticity can be realized.

According to an embodiment of the present disclosure, there is provideda light emitting device which includes a plurality of organicelectroluminescent sections each including a first electrode layer, anorganic light emitting layer, a second electrode layer having a filmthickness of not less than 15 nm and a reflective layer in this order,and a light extraction surface from which light emitted from each of theorganic electroluminescent sections through the reflective layer isextracted. The reflective layer includes two reflective interfaces. Ineach of the organic electroluminescent sections, a microcavity structureis formed by a structure including a first reflective interface on theorganic light emitting layer side of the first electrode layer, a secondreflective interface on the organic light emitting layer side of thesecond electrode layer, and the two reflective interfaces included inthe reflective layer. The plurality of organic electroluminescentsections include a plurality of first organic electroluminescentsections that emit light in a first wavelength band, and a plurality ofsecond organic electroluminescent sections that emit light in a secondwavelength band on a shorter wavelength side than the first wavelengthband. In each of the first organic electroluminescent sections and eachof the second organic electroluminescent sections, the microcavitystructure is configured in such a manner that the first reflectiveinterface and the second reflective interface intensify the light in thefirst wavelength band and the light in the second wavelength band, andthat the two reflective interfaces included in the reflective layerweaken the light in the first wavelength band and intensify the light inthe second wavelength band.

According to the light emitting device of the embodiment of the presentdisclosure, worsening of viewing angle characteristic of chromaticitycan be restrained even in the case where the second electrode layer isenlarged in film thickness. Therefore, both good feed performance andgood viewing angle characteristic of chromaticity can be secured. Notethat the advantageous effects described here are not limitative, and theeffects of the present disclosure may be any of the effects describedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view depicting a general configuration of a lightemitting device according to an embodiment of the present disclosure;

FIG. 2 is a sectional view depicting the configuration of a red lightemitting section illustrated in FIG. 1;

FIG. 3 is a sectional view depicting the configuration of a green lightemitting section illustrated in FIG. 1;

FIG. 4 is a sectional view depicting the configuration of a blue lightemitting section illustrated in FIG. 1;

FIG. 5 is a sectional view for explaining an operation of the lightemitting device illustrated in FIG. 1;

FIG. 6 is a diagram depicting an example of a variation in chromaticitywith viewing angle, in a light emitting device according to acomparative example;

FIG. 7 is another diagram depicting an example of a variation inchromaticity with viewing angle, in the light emitting device accordingto the comparative example;

FIG. 8 is a diagram depicting an example of a variation in chromaticitywith viewing angle, in the light emitting device illustrated in FIG. 1;

FIG. 9 is a diagram depicting an example of a variation in 45-degreechromaticity viewing angle with film thickness of an electrode on thelight extraction surface side, in the light emitting device according tothe comparative example;

FIG. 10 is a diagram depicting an example of a variation in relativeluminance with film thickness of the electrode on the light extractionsurface side, in the light emitting device according to the comparativeexample;

FIG. 11 is a sectional view depicting a modification of theconfiguration of the light emitting section illustrated in FIG. 1;

FIG. 12 is a figure depicting a general configuration of a displaydevice obtained by application of the light emitting device illustratedin FIG. 1, etc.;

FIG. 13 is a circuit diagram depicting a circuit configuration of apixel illustrated in FIG. 12;

FIG. 14 is a figure depicting an example of appearance of an electronicapparatus obtained by application of the display device illustrated inFIG. 12; and

FIG. 15 is a figure depicting an example of appearance of anillumination apparatus obtained by application of the light emittingdevice illustrated in FIG. 1, etc.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present disclosure will be described in detailbelow, referring to the drawings, in the following order.

1. Embodiment (Light emitting device)

2. Modification (Light emitting device)

3. Application examples (Display device, Electronic apparatus,Illumination apparatus)

1. Embodiment Configuration

FIG. 1 depicts a sectional configuration of a major part of a lightemitting device 1 according to an embodiment of the present disclosure.The light emitting device 1 includes a substrate 11, over which aplurality of red light emitting sections 10R, a plurality of green lightemitting sections 10G and a plurality of blue light emitting sections10B are provided. The red light emitting section 10R corresponds to aspecific example of the “organic electroluminescent section” and the“first organic electroluminescent section” in the present disclosure.The green light emitting section 10G corresponds to a specific exampleof the “organic electroluminescent section” and the “first organicelectroluminescent section” in the present disclosure. The blue lightemitting section 10B corresponds to a specific example of the “organicelectroluminescent section” and the “second organic electroluminescentsection” in the present disclosure.

The red light emitting section 10R includes an electrode layer 12R, ared organic layer 13R including a red light emitting layer 131R, anelectrode layer 14R, a transparent layer 15R, a transparent layer 16Rand a transparent layer 17R in this order over the substrate 11. Thegreen light emitting section 10G includes an electrode layer 12G, agreen organic layer 13G including a green light emitting layer 131G, anelectrode layer 14G, a transparent layer 15G, a transparent layer 16Gand a transparent layer 17G in this order over the substrate 11. Theblue light emitting section 10B includes an electrode layer 12B, a blueorganic layer 13B including a blue light emitting layer 131B, anelectrode layer 14B, a transparent layer 15B, a transparent layer 16Band a transparent layer 17B in this order over the substrate 11. Theelectrode layers 12R, 12G and 12B correspond to specific examples of the“first electrode layer” in the present disclosure. The electrode layers14R, 14G and 14B correspond to specific examples of the “secondelectrode layer” in the present disclosure. A laminate including thetransparent layer 15R, the transparent layer 16R and the transparentlayer 17R corresponds to a specific example of the “reflective layer” inthe present disclosure. A laminate including the transparent layer 15G,the transparent layer 16G and the transparent layer 17G corresponds to aspecific example of the “reflective layer” in the present disclosure. Alaminate including the transparent layer 15B, the transparent layer 16Band the transparent layer 17B corresponds to a specific example of the“reflective layer” in the present disclosure.

The red light emitting section 10R emits light in a red wavelengthregion (red light LR) generated in the red light emitting layer 131R bycurrent injection by the electrode layer 12R and the electrode layer14R, from the transparent layer 17R side. The green light emittingsection 10G emits light in a green wavelength region (green light LG)generated in the green light emitting layer 131G by current injection bythe electrode layer 12G and the electrode layer 14G, from thetransparent layer 17G side. The blue light emitting section 10B emitslight in a blue wavelength region (blue light LB) generated in the bluelight emitting layer 131B by current injection by the electrode layer12B and the electrode layer 14B, from the transparent layer 17B side.The light emitting device 1 is configured such that the lights generatedfrom the red light emitting layer 131R, the green light emitting layer131G and the blue light emitting layer 131B are subjected to multiplereflection between the electrode layers 12R, 12G and 12B and thetransparent layers 17R, 17G and 17B and the lights are extracted fromthe transparent layer 17G, 17G and 17B side. In other words, the lightemitting device 1 is a top emission type light emitting device having aresonator structure.

The substrate 11 is a plate-shaped member for supporting the red lightemitting layers 131R, the green light emitting layers 131G and the bluelight emitting layers 131B, and includes, for example, a transparentglass substrate or semiconductor substrate or the like. The substrate 11may include a flexible substrate. The substrate may be a circuitsubstrate provided with a circuit or circuits (a pixel circuit orcircuits 18-1 described later) for driving the red light emitting layers131R, the green light emitting layers 131G and the blue light emittinglayers 131B.

The electrode layers 12R, 12G and 12B are anode electrodes, and functionalso as reflecting mirrors. The electrode layers 12R, 12G and 12B areformed using a light-reflective material, for example. Examples of thelight-reflective material used for the electrode layers 12R, 12G and 12Binclude aluminum (Al), aluminum alloys, platinum (Pt), gold (Au),chromium (Cr), and tungsten (W). The electrode layers 12R, 12G and 12Bmay be configured, for example, by stacking a transparent conductivematerial and a light-reflective material. The thicknesses of theelectrode layers 12R, 12G and 12B are, for example, 100 to 300 nm.

The red organic layer 13R includes, for example, a hole injection layer,a hole transport layer, the red light emitting layer 131R, an electrontransport layer and an electron injection layer in this order from aposition near the electrode layer 12R. The green organic layer 13Gincludes, for example, a hole injection layer, a hole transport layer,the green light emitting layer 131G, an electron transport layer and anelectron injection layer in this order from a position near theelectrode layer 12G. The blue organic layer 13B includes, for example, ahole injection layer, a hole transport layer, the blue light emittinglayer 131B, an electron transport layer and an electron injection layerin this order from a position near the electrode layer 12B.

The hole injection layer is a layer for preventing leakage. The holeinjection layer is formed, for example, by using hexaazatriphenylene(HAT) or the like. The thickness of the hole injection layer is, forexample, 1 to 20 nm. The hole transport layer is formed, for example, byusing α-NPD[N,N′-di(1-naphthyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine]. Thethickness of the hole transport layer is, for example, 15 to 100 nm.

The red light emitting layer 131R, the green light emitting layer 131Gand the blue light emitting layer 131B are each configured to emit lightin a predetermined color by coupling of holes and electrons. Thethicknesses of the red light emitting layer 131R, the green lightemitting layer 131G and the blue light emitting layer 131B are, forexample, 5 to 50 nm. The red light emitting layer 131R emits light inthe red wavelength region (first wavelength band). The red lightemitting layer 131R is formed, for example, by using rubrene doped witha pyrromethene boron complex. In this instance, rubrene is used as ahost material. The green light emitting layer 131G emits light in thegreen wavelength region (first wavelength band). The green lightemitting layer 131G is formed, for example, by using Alq3(tris-quinolinol aluminum complex). The blue light emitting layer 131Bemits light in the blue wavelength region on the shorter wavelength sidethan the red wavelength region (in a second wavelength band on theshorter wavelength side than the first wavelength band). The blue lightemitting layer 131B is formed, for example, by using ADN(9,10-di(2-naphthyl)anthracene) doped with a diaminochrysene derivative.In this instance ADN is used as a host material, and is a vapordeposited film having a thickness of 20 nm, for example. Thediaminochrysene derivative is used as a dopant material, and the dopingis, for example, 5% doping in terms of relative film thickness ratio.

The electron transport layer is formed by using BCP(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline). The thickness of theelectron transport layer is, for example, 15 to 200 nm. The electroninjection layer is formed, for example, by using lithium fluoride (LiF).The thickness of the electron injection layer is, for example, 15 to 270nm.

The electrode layers 14R, 14G and 14B are cathode electrodes, andfunction also as reflecting mirrors. The electrode layers 14R, 14G and14B are each formed by using a metallic material high in reflectance.The electrode layers 14R, 14G and 14B are each formed, for example, byusing any of magnesium (Mg), silver (Ag) and their alloys. The electrodelayers 14R, 14G and 14B are each composed, for example, of a singlemetal layer which has a thickness of 15 to 55 nm. With the electrodelayers 14R, 14G and 14B formed by using such metallic materials high inreflectance, the effect of the resonator structure is enhanced, andlight extraction efficiency can be enhanced. As a result, it is possibleto suppress power consumption and to prolong the useful lives of the redlight emitting section 10R, the green light emitting section 10G and theblue light emitting section 10B. Note that where the light extractionefficiency and the resistance values of the electrode layers 14R, 14Gand 14B at the time when the thicknesses of the electrode layers 14R,14G and 14B are 15 nm are taken as reference, the upper limit of thethicknesses of the electrode layers 14R, 14G and 14B such that theproduct of current ratio (reciprocal of relative efficiency) andresistance ratio is not less than 1 is 55 nm.

The transparent layers 15R, 15G and 15B, the transparent layers 16R, 16Gand 16B and the transparent layers 17R, 17G and 17B are provided on thelight extraction side in the light emitting device 1. The thicknesses ofthe transparent layers 15R, 15G and 15B are, for example, 30 to 450 nm;the thicknesses of the transparent layers 16R, 16G and 16B are, forexample, 30 to 380 nm; and the thicknesses of the transparent layers17R, 17G and 17B are, for example, 500 to 10,000 nm.

The transparent layers 15R, 15G and 15B, the transparent layers 16R, 16Gand 16B and the transparent layers 17R, 17G and 17B are each formed, forexample, by using a transparent conductive material or a transparentdielectric material. Examples of the transparent conductive materialused for the transparent layers 15R, 15G and 15B, the transparent layers16R, 16G and 16B and the transparent layers 17R, 17G and 17B include ITO(Indium Tin Oxide), and an oxide of indium and zinc (IZO). Examples ofthe transparent dielectric material used for the transparent layers 15R,15G and 15B, the transparent layers 16R, 16G and 16B and the transparentlayers 17R, 17G and 17B include silicon oxide (SiO₂), silicon oxynitride(SiON) and silicon nitride (SiN). The transparent layers 15R, 15G and15B, the transparent layers 16R, 16G and 16B and the transparent layers17R, 17G and 17B may function as cathode electrodes, or may beconfigured to function as passivation films. Low-refractive-indexmaterials such as MgF and NaF may also be used for the transparentlayers 15R, 15G and 15B, the transparent layers 16R, 16G and 16B and thetransparent layers 17R, 17G and 17B.

A layer having a film thickness of not less than 1 μm may be provided onthe upper side of the transparent layers 17R, 17G and 17B. This layer isformed, for example, by using a transparent conductive material, atransparent insulating material, a resin material, a glass or the like.This layer may include air. With such a layer provided, the resonatorstructures configured between the electrode layers 12R, 12G and 12B andthe transparent layers 17R, 17G and 17B can be protected from externalinterference.

The resonator structures of the red light emitting section 10R, thegreen light emitting section 10G and the blue light emitting section 10Bwill be described below. FIG. 2 is a sectional view depicting theconfiguration of the red light emitting section 10R. FIG. 3 is asectional view depicting the configuration of the green light emittingsection 10G. FIG. 4 is a sectional view depicting the configuration ofthe blue light emitting section 10B.

The red light emitting section 10R includes a first reflective interfaceS1R, a second reflective interface S2R, a third reflective interfaceS3R, a fourth reflective interface S4R and a light extraction surfaceSDR in this order from the substrate 11 side. The third reflectiveinterface S3R and the fourth reflective interface S4R are included in alaminate including the transparent layer 15R, the transparent layer 16Rand the transparent layer 17R. In this instance, a microcavity structureis formed by a structure including the first reflective interface S1R,the second reflective interface S2R, the third reflective interface S3Rand the fourth reflective interface S4R. The microcavity structure has,for example, an effect to intensify light of a specified wavelength(e.g., light in the red wavelength region) by utilizing the resonance oflight generated between the electrode layer 12R and the electrode layer14R. A light emission center OR of the red light emitting layer 131R isprovided between the first reflective interface S1R and the secondreflective interface S2R. In other words, the red light emitting layer131R is provided between the first reflective interface S1R and thelight extraction surface SDR which are opposed to each other. The firstreflective interface S1R is an interface between the electrode layer 12Rand the red organic layer 13R. The second reflective interface S2R is aninterface between the red organic layer 13R and the electrode layer 14R.The third reflective interface S3R is an interface between thetransparent layer 15R and the transparent layer 16R. The fourthreflective interface S4R is an interface between the transparent layer16R and the transparent layer 17R. The light extraction surface SDR isan outermost surface of the red light emitting section 10R. Theoutermost surface of the red light emitting section 10R is in contactwith an air layer, for example. Light emitted from the red lightemitting section 10R through the transparent layers 15R, 16R and 17R isextracted from the light extraction surface SDR.

The green light emitting section 10G includes a first reflectiveinterface S1G, a second reflective interface S2G, a third reflectiveinterface S3G, a fourth reflective interface S4G and a light extractionsurface SDG in this order from the substrate 11 side. The thirdreflective interface S3G and the fourth reflective interface S4G areincluded in a laminate including the transparent layer 15G, thetransparent layer 16G and the transparent layer 17G. In this instance, amicrocavity structure is formed by a structure including the firstreflective interface S1G, the second reflective interface S2G, the thirdreflective interface S3G and the fourth reflective interface S4G. themicrocavity structure has, for example, an effect to intensify light ofa specified wavelength (e.g., light in the green wavelength region) byutilizing the resonance of light generated between the electrode layer12G and the electrode layer 14G. A light emission center OG of the greenlight emitting layer 131G is provided between the first reflectiveinterface S1G and the second reflective interface S2G. In other words,the green light emitting layer 131G is provided between the firstreflective interface S1G and the light extraction surface SDG which areopposed to each other. The first reflective interface S1G is aninterface between the electrode layer 12G and the green organic layer13G. The second reflective interface S2G is an interface between thegreen organic layer 13G and the electrode layer 14G. The thirdreflective interface S3G is an interface between the transparent layer15G and the transparent layer 16G. The fourth reflective interface S4Gis an interface between the transparent layer 16G and the transparentlayer 17G. The light extraction surface SDG is an outermost surface ofthe green light emitting section 10G. The outermost surface of the greenlight emitting section 10G is in contact with an air layer, for example.Light emitted from the green light emitting section 10G through thetransparent layers 15G, 16G and 17G is extracted from the lightextraction surface SDG.

The blue light emitting section 10B includes a first reflectiveinterface S1B, a second reflective interface S2B, a third reflectiveinterface S3B, a fourth reflective interface S4B and a light extractionsurface SDB in this order from the substrate 11 side. The thirdreflective interface S3B and the fourth reflective interface S4B areincluded in a laminate including the transparent layer 15B, thetransparent layer 16B and the transparent layer 17B. In this instance, amicrocavity structure is formed by a structure including the firstreflective interface S1B, the second reflective interface S2B, the thirdreflective interface S3B and the fourth reflective interface S4B. Themicrocavity structure has, for example, an effect to intensify light ofa specified wavelength (e.g., light in the blue wavelength region) byutilizing the resonance of light generated between the electrode layer12B and the electrode layer 14B. A light emission center OB of the bluelight emitting layer 131B is provided between the first reflectiveinterface S1B and the second reflective interface S2B. In other words,the blue light emitting layer 131B is provided between the firstreflective interface S1B and the light extraction surface SDB which areopposed to each other. The first reflective interface S1B is aninterface between the electrode layer 12B and the blue organic layer13B. The second reflective interface S2B is an interface between theblue organic layer 13B and the electrode layer 14B. The third reflectiveinterface S3B is an interface between the transparent layer 15B and thetransparent layer 16B. The fourth reflective interface S4B is aninterface between the transparent layer 16B and the transparent layer17B. The light extraction surface SDB is an outermost surface of theblue light emitting section 10B. The outermost surface of the blue lightemitting section 10B is in contact with an air layer, for example. Lightemitted from the blue light emitting section 10B through the transparentlayers 15B, 16B and 17B is extracted from the light extraction surfaceSDB.

The first reflective interfaces S1R, S1G and S1B and the secondreflective interfaces S2R, S2G and S2B each include a reflective filmformed by using a metal. The third reflective interfaces S3R, S3G andS3B and the fourth reflective interfaces S4R, S4G and S4B each includean interface having a refractive index difference of not less than 0.15,for example.

First Reflective Interfaces S1R, S1G and S1B

Let the electrode layers 12R, 12G and 12B be each formed by usingaluminum (Al) having a refractive index of 0.73 and an extinctioncoefficient of 5.91, and let the red organic layer 13R, the greenorganic layer 13G and the blue organic layer 13B be each formed by usinga material having a refractive index of 1.75. In this instance, thefirst reflective interface S1R is disposed at a position of an opticalpath La1 from the light emission center OR, the first reflectiveinterface S1G is disposed at a position of an optical path Lb1 from thelight emission center OG, and the first reflective interface S1B isdisposed at a position of an optical path Lc1 from the light emissioncenter OB.

The optical path La1 is set in such a manner that the light with acenter wavelength λa in the light emission spectrum of the red lightemitting layer 131R (the light in the red wavelength region (firstwavelength band)) is intensified by interference between the firstreflective interface S1R and the light emission center OR. The opticalpath Lb1 is set in such a manner that the light with a center wavelengthλb in the light emission spectrum of the green light emitting layer 131G(the light in the green wavelength region (first wavelength band)) isintensified by interference between the first reflective interface S1Gand the light emission center OG. The optical path Lc1 is set in such amanner that the light with a center wavelength λc in the light emissionspectrum of the blue light emitting layer 131B (the light in the bluewavelength region (second wavelength band)) is intensified byinterference between the first reflective interface S1B and the lightemission center OB.

Specifically, the optical paths La1, Lb1 and Lc1 satisfy the followingexpressions (1) to (6).2La1/λa1+φa1/(2π)=Na  (1)λa−150<λa1<λa+80  (2)2Lb1/λb1+φb1/(2π)=Nb  (3)λb−150<λb1<λb+80  (4)2Lc1/λc1+φc1/(2π)=Nc  (5)λc−150<λc1<λc+80  (6)whereNa, Nb and Nc are each an integer of not less than 0;the unit of λa, λa1, λb, λb1, λc and λc1 is nm;φa1 is the phase change when the light emitted from the red lightemitting layer 131R is reflected by the first reflective interface S1R;φb1 is the phase change when the light emitted from the green lightemitting layer 131G is reflected by the first reflective interface S1G;φc1 is the phase change when the light emitted from the blue lightemitting layer 131B is reflected by the first reflective interface S1B;λa1 is a wavelength satisfying the expression (2);λb1 is a wavelength satisfying the expression (4); andλc1 is a wavelength satisfying the expression (6).φa1, φb1 and φc1 can be calculated by use of n0 and k values of thecomplex refractive indexes N=n0−jk (n0 is refractive index, and k isextinction coefficient) of the constituent materials of the electrodelayers 12R, 12G and 12B and the refractive indexes of the red organiclayer 13R, the green organic layer 13G and the blue organic layer 13B(see, for example, Principles of Optics, Max Born and Emil Wolf, 1974(PERGAMON PRESS)). The refractive indexes of the constituent materialscan be measured by use of a spectroscopic ellipsometry measuringinstrument.

When the values of Na, Nb and Nc are high, the so-called microcavity(minute resonator) effect cannot be obtained. Therefore, it ispreferable that Na=0, Nb=0, and Nc=0. In the case where the optical pathLa1 satisfies the above expressions (1) and (2), λa1 can be largelydeviated from the center wavelength λa. Similarly, in the case where theoptical path Lb1 satisfies the above expressions (3) and (4), λ1 can belargely deviated from the center wavelength λb. Besides, in the casewhere the optical path Lc1 satisfies the above expressions (5) and (6),λc1 can be largely deviated from the center wavelength λc.

Second Reflective Interfaces S2R, S2G and S2B

Let the red organic layer 13R, the green organic layer 13G and the blueorganic layer 13B be each formed by using a material having a refractiveindex of 1.75, and let the electrode layers 14R, 14G and 14B be eachformed by using silver (Ag) having a refractive index of 0.13 and anextinction coefficient of 3.96. In this instance, the second reflectiveinterface S2R is disposed at a position of an optical path La2 from thelight emission center OR, the second reflective interface S2G isdisposed at a position of an optical path Lb2 from the light emissioncenter OG, and the second reflective interface S2B is disposed at aposition of an optical path Lc2 from the light emission center OB.

The optical path La2 is set in such a manner that the light with acenter wavelength λa in the light emission spectrum of the red lightemitting layer 131R (the light in the red wavelength region (firstwavelength band)) is intensified by interference between the secondreflective interface S2R and the light emission center OR. The opticalpath Lb2 is set in such a manner that the light with a center wavelengthλb in the light emission spectrum of the green light emitting layer 131G(the light in the green wavelength region (first wavelength band)) isintensified by interference between the second reflective interface S2Gand the light emission center OG. The optical path Lc2 is set in such amanner that the light with a center wavelength λc in the light emissionspectrum of the blue light emitting layer 131B (the light in the bluewavelength region (second wavelength band)) is intensified byinterference between the second reflective interface S2B and the lightemission center OB.

Specifically, the optical paths La2, Lb2 and Lc2 satisfy the followingexpressions (7) to (12).2La2/λa2+φa2/(2π)=Ma  (7)λa−80<λa2<λa+80  (8)2Lb2/λb2+φb2/(2π)=Mb  (9)λb−80<λb2<λb+80  (10)2Lc2/λc2+φc2/(2π)=Mc  (11)λc−80<λc2<λc+80  (12)whereMa, Mb and Mc are each an integer of not less than 0;the unit of λa, λa2, λb, λb2, λc and λc2 is nm;φa2 is the phase change when the light emitted from the red lightemitting layer 131R is reflected by the second reflective interface S2R;φb2 is the phase change when the light emitted from the green lightemitting layer 131G is reflected by the second reflective interface S2G;φc2 is the phase change when the light emitted from the blue lightemitting layer 131B is reflected by the second reflective interface S2B;λa2 is a wavelength satisfying the expression (8);λb2 is a wavelength satisfying the expression (10); andλc2 is a wavelength satisfying the expression (12).φa2, φb2 and φc2 can be determined by a method similar to that for φa1,φb1 and φc1. When the values of Ma, Mb and Mc are high, the so-calledmicrocavity (minute resonator) effect cannot be obtained. Therefore, itis preferable that Ma=0, Mb=0, and Mc=0.

Here, it is presumed that Na=0, Nb=0, Nc=0, Ma=0, Mb=0, and Mc=0. Inthis case, a microcavity structure with a minimum resonance condition isformed by a structure including the first reflective interface S1R, thesecond reflective interface S2R, the third reflective interface S3R andthe fourth reflective interface S4R. In this instance, the microcavitystructure with the minimum resonance condition of the red light emittingsection 10R is configured in such a manner that the first reflectiveinterface S1R and the second reflective interface S2R intensify light inthe red wavelength region, and that the third reflective interface S3Rand the fourth reflective interface S4R weaken the light in the redwavelength region. Similarly, a microcavity structure with a minimumresonance condition is formed by a structure including the firstreflective interface S1G, the second reflective interface S2G, the thirdreflective interface S3G and the fourth reflective interface S4G. Inthis instance, the microcavity structure with the minimum resonancecondition of the green light emitting section 10G is configured in sucha manner that the first reflective interface S1G and the secondreflective interface S2G intensify light in the green wavelength region,and that the third reflective interface S3G and the fourth reflectiveinterface S4G weaken the light in the green wavelength region. Further,a microcavity structure with a minimum resonance condition is formed bya structure including the first reflective interface S1B, the secondreflective interface S2B, the third reflective interface S3B and thefourth reflective interface S4B. In this instance, the microcavitystructure with the minimum resonance condition of the blue lightemitting section 10B is configured in such a manner that the firstreflective interface S1B and the second reflective interface S2Bintensify light in the blue wavelength region, and that the thirdreflective interface S3B and the fourth reflective interface S4Bintensify the light in the blue wavelength region.

In the case where the optical path La1 satisfies the above-mentionedexpressions (1) and (2) and where the optical path La2 satisfies theabove-mentioned expressions (7) and (8), a peak of transmittance isgenerated at a predetermined wavelength due to an amplifying effect ofthe first reflective interface S1R and the second reflective interfaceS2R. In the case where the optical path Lb1 satisfies theabove-mentioned expressions (3) and (4) and where the optical path Lb2satisfies the above-mentioned expressions (9) and (10), a peak oftransmittance is generated at a predetermined wavelength due to anamplifying effect of the first reflective interface S1G and the secondreflective interface S2G. In the case where the optical path Lc1satisfies the above-mentioned expressions (5) and (6) and where theoptical path Lc2 satisfies the above-mentioned expressions (11) and(12), a peak of transmittance is generated at a predetermined wavelengthdue to an amplifying effect of the first reflective interface S1B andthe second reflective interface S2B.

Third Reflective Interfaces S3R, S3G and S3B

The optical path La3 is set, for example, in such a manner that thelight with a center wavelength λa in the light emission spectrum of thered light emitting layer 131R is weakened by interference between thethird reflective interface S3R and the light emission center OR. In thisinstance, the optical path between the second reflective interface S2Rand the third reflective interface S3R is not more than the centerwavelength λa of the light emitted from the red light emitting layer131R. The optical path Lb3 is set, for example, in such a manner thatthe light with a center wavelength λb in the light emission spectrum ofthe green light emitting layer 131G is weakened by interference betweenthe third reflective interface S3G and the light emission center OG. Inthis instance, the optical path between the second reflective interfaceS2G and the third reflective interface S3G is not more than the centerwavelength λb of the light emitted from the green light emitting layer131G. The optical path Lc3 is set, for example, in such a manner thatthe light with a center wavelength λc in the light emission spectrum ofthe blue light emitting layer 131B is intensified by interferencebetween the third reflective interface S3B and the light emission centerOB. In this instance, the optical path between the second reflectiveinterface S2B and the third reflective interface S3B is not more thanthe center wavelength λc of the light emitted from the blue lightemitting layer 131B.

The optical paths La3, Lb3 and Lc3 satisfy, for example, the followingexpressions (13) to (18).2La3/λa3+φa3/(2π)=Ka+½  (13)λa−150<λa3<λa+150  (14)2Lb3/λb3+φb3/(2π)=Kb+½  (15)λb−150<λb3<λb+150  (16)2Lc3/λc3+φc3/(2π)=Kc  (17)λc−150<λc3<λc+150  (18)whereKa, Kb and Kc are each an integer of not less than 0;the unit of λa, λa3, λb, λb3, λc and λc3 is nm;φa3 is the phase change when the light emitted from the red lightemitting layer 131R is reflected by the third reflective interface S3R;φb3 is the phase change when the light emitted from the green lightemitting layer 131G is reflected by the third reflective interface S3G;φc3 is the phase change when the light emitted from the blue lightemitting layer 131B is reflected by the third reflective interface S3B;λa3 is a wavelength satisfying the expression (14);λb3 is a wavelength satisfying the expression (16); andλc3 is a wavelength satisfying the expression (18).φa3, φb3 and φc3 can be determined by a method similar to that for φa1,φb1 and φc1. In the case where the optical paths La3, Lb3 and Lc3satisfy the above expressions (13) to (18), the light emitting state canbe adjusted on the light emitting section (the red light emittingsection 10R, the green light emitting section 10G, the blue lightemitting section 10B) basis. Thus, by the addition of the reflection onthe third reflective interface S3R, the light generated in the red lightemitting layer 131R is weakened, and the half-value width of thespectrum is broadened. In addition, by the addition of the reflectanceon the third reflective interface S3G, the light generated in the greenlight emitting layer 131G is weakened, and the half-value width of thespectrum is broadened. By the addition of the reflection on the thirdreflective interface S3B, the light generated in the blue light emittinglayer 131B is intensified, and the half-value width of the spectrum isnarrowed.

Fourth Reflective Interfaces S4R, S4G and S4B

The optical path La4 is set, for example, in such a manner that thelight with a center wavelength λa in the light emission spectrum of thered light emitting layer 131R is weakened by interference between thefourth reflective interface S4R and the light emission center OR. Inthis instance, the optical path between the second reflective interfaceS2R and the fourth reflective interface S4R is not more than the centerwavelength λa of the light emitted from the red light emitting layer131R. The optical path Lb4 is set, for example, in such a manner thatthe light with a center wavelength λb in the light emission spectrum ofthe green light emitting layer 131G is weakened by interference betweenthe fourth reflective interface S4G and the light emission center OG. Inthis instance, the optical path between the second reflective interfaceS2G and the fourth reflective interface S4G is not more than the centerwavelength λb of the light emitted from the green light emitting layer131G. The optical path Lc4 is set, for example, in such a manner thatthe light with a center wavelength λc in the light emission spectrum ofthe blue light emitting layer 131B is intensified by interferencebetween the fourth reflective interface S4B and the light emissioncenter OB. In this instance, the optical path between the secondreflective interface S2B and the fourth reflective interface S4B is notmore than the center wavelength λc of the light emitted from the bluelight emitting layer 131B.2La4/λa4+φa4/(2π)=Ja+½  (19)λa−150<λa4<λa+150  (20)2Lb4/λb4+φb4/(2π)=Jb+½  (21)λb−150<λb4<λb+150  (22)2Lc4/λc4+φc4/(2π)=Jc  (23)λc−150<λc4<λc+150  (24)whereJa, Jb and Jc are each an integer of not less than 0;the unit of λa, λa4, λb, λb4, λc and λc4 is nm;φa4 is the phase change when the light emitted from the red lightemitting layer 131R is reflected by the fourth reflective interface S4R;φb4 is the phase change when the light emitted from the green lightemitting layer 131G is reflected by the fourth reflective interface S4G;φc4 is the phase change when the light emitted from the blue lightemitting layer 131B is reflected by the fourth reflective interface S4B;φa4 is a wavelength satisfying the expression (20);φb4 is a wavelength satisfying the expression (22); andφc4 is a wavelength satisfying the expression (24).φa4, φb4 and φc4 can be determined by a method similar to that for φa1,φb1 and φc1. In the case where the optical paths La3, Lb3 and Lc3satisfy the above-mentioned expressions (13) to (18) and where theoptical paths La4, Lb4 and Lc4 satisfy the above expressions (19) to(24), the light emitting state can be adjusted on the light emittingsection (the red light emitting section 10R, the green light emittingsection 10G, the blue light emitting section 10B) basis. Thus, by theaddition of the reflection on the fourth reflective interfaces S4R, S4Gand S4B, the peak profiles of the spectra of the lights generated in thered light emitting layer 131R, the green light emitting layer 131G andthe blue light emitting layer 131B can be adjusted to desired profiles.As a result, it is possible, for example, to restrain sudden variationsin luminance and hue with angle. In addition, for example, by causingthe spectrum of the light generated in the light emitting layer to havea steep peak, it is possible to enhance light extraction efficiency.Besides, it is also possible to improve chromaticity point.

Such a light emitting device 1 can be manufactured by forming theelectrode layers 12R, 12G and 12B, the organic layers (the red organiclayer 13R, the green organic layer 13G, and the blue organic layer 13B),the electrode layers 14R, 14G and 14B, the transparent layers 15R, 15Gand 15B, the transparent layers 16R, 16G and 16B and the transparentlayers 17R, 17G and 17B in this order over the substrate 11. The redorganic layers 13R, the green organic layers 13G and the blue organiclayers 13B may be formed by a vapor deposition method or may be formedby printing. In other words, the red organic layers 13R, the greenorganic layers 13G and the blue organic layers 13B may be printedlayers. The electrode layers 14R, 14G and 14B may be composed of acommon layer. In this case, the materials and thicknesses of theelectrode layers 14R, 14G and 14B are equal to one another. Thetransparent layers 15R, 15G and 15B may be composed of a common layer.In this case, the materials and thicknesses of the transparent layers15R, 15G and 15B are equal to one another. The transparent layers 16R,16G and 16B may be composed of a common layer. In this case, thematerials and thicknesses of the transparent layers 16R, 16G and 16B areequal to one another. The transparent layers 17R, 17G and 17B may becomposed of a common layer. In this case, the materials and thicknessesof the transparent layers 17R, 17G and 17B are equal to one another.

Operation and Effect

In the light emitting device 1 as above-described, a driving current isinjected into each of the light emitting layers (the red light emittinglayer 131R, the green light emitting layer 131G, and the blue lightemitting layer 131B) of the red light emitting section 10R, the greenlight emitting section 10G and the blue light emitting section 10Bthrough the electrode layers 12R, 12G and 12B and the electrode layers14R, 14G and 14B. As a result, in each light emitting layer,recombination of holes and electrons occurs, to produce exitons, therebyemitting light.

For example, as illustrated in FIG. 5, the light produced in the redorganic layer 13R is subjected to multiple reflection between the firstreflective interface S1R and the fourth reflective interface S4R, and isextracted from the light extraction surface SDR. Red light LR isextracted from the light extraction surface SDR in the red lightemitting section 10R, green light LG is extracted from the lightextraction surface SDG in the green light emitting section 10G, and bluelight LB is extracted from the light extraction surface SDB in the bluelight emitting section 10B. By additive mixture of the red light LR, thegreen light LG and the blue light LB, various colors are expressed.

In the light emitting device having such a resonator structure, however,it is difficult to enhance light distribution characteristics, althoughvarious structures have been proposed.

For instance, in order that light of a desired wavelength is resonated,a method of setting a film thickness between a light-transmittingelectrode and a reflective electrode to thereby enhance light emissionefficiency has been proposed (see, for example, WO 01/039554). Inaddition, an attempt to control the balance of attenuation of threeprimary colors (red, green and blue) by controlling the film thicknessesof the organic layers and to enhance viewing angle characteristics ofchromaticity point of white color has also been made (see, for example,JP 2011-159433A).

However, such a resonator structure functions as an interference filterwith a narrow half-value width for the spectrum of the light extracted,and, therefore, the wavelength of the light is largely shifted in thecase where the light extraction surface is viewed from an obliquedirection. Accordingly, a lowering in light emission intensity or thelike is generated depending on the viewing angle, and viewing angledependency is increased.

In addition, JP 2006-244713A proposes a structure for reducing a changein chromaticity depending on viewing angle. However, although thisstructure may be applied to monochrome and may be able to reducedependency of luminance on viewing angle, it is difficult to apply thestructure to a sufficiently wide wavelength band. While it may becontemplated to enhance reflectance in order to broaden the wavelengthband to which the structure is applicable, in that case, lightextraction efficiency is lowered conspicuously.

A method of reducing the angle dependency by adjusting the positionalrelations in the resonator structure, the light emission position andthe like may be contemplated as above-mentioned, but this method maylead to a case where adjustment is difficult. Examples of such a caseinclude a case where wavelength dispersion of refractive index isgenerated depending on the spectrum of the light emitted from each lightemitting layer. In the case of the wavelength dispersion of refractiveindex, since the refractive index of a constituent material is differentfor different wavelengths, differences in the effect of the resonatorstructure would be generated between the red organic EL element, thegreen organic EL element and the blue organic EL element. For example,in the red organic EL element, the peak of the red light extracted istoo steep, and, in the blue organic EL element, the peak of the bluelight extracted is too gentle. When the effect of the resonatorstructure is thus largely differing on the element region basis, theangle dependencies of luminance and chromaticity are increased, andlight distribution characteristics are lowered.

On the other hand, in the light emitting device 1 according to thepresent embodiment, the influence of the third reflective interface S3Rand the fourth reflective interface S4R on the light generated in thered light emitting layer 131R and the influence of the third reflectiveinterface S3B and the fourth reflective interface S4B on the lightgenerated in the blue light emitting layer 131B are different from eachother. Similarly, in the light emitting device 1 according to thepresent embodiment, the influence of the third reflective interface S3Gand the fourth reflective interface S4G on the light generated in thegreen light emitting layer 131G and the influence of the thirdreflective interface S3B and the fourth reflective interface S4B on thelight generated in the blue light emitting layer 131B are different fromeach other. For example, the lights generated in the red light emittinglayer 131R, the green light emitting layer 131G and the blue lightemitting layer 131B are as follows.

The light generated in the red light emitting layer 131R is weakened bythe interferences between the light emission center OR of the red lightemitting layer 131R and the third reflective interface S3R and thefourth reflective interface S4R of the red light emitting layer 131R.Similarly, the light generated in the green light emitting layer 131G isweakened by the interferences between the light emission center OG ofthe green light emitting layer 131G and the third reflective interfaceS3G and the fourth reflective interface S4G of the green light emittinglayer 131G. On the other hand, the light generated in the blue lightemitting layer 131B is intensified by the interferences between thelight emission center OB of the blue light emitting layer 131B and thethird reflective interface S3B and the fourth reflective interface S4B.

As a result, red light LR which is gentle in the vicinity of a peak isextracted from the light extraction surface SDR in the red lightemitting section 10R, green light LG which is gentle in the vicinity ofa peak is extracted from the light extraction surface SDG in the greenlight emitting section 10G, and blue light LB which has a steep peak isextracted from the light extraction surface SDB in the blue lightemitting section 10B. Therefore, the difference between the effect ofthe resonator structures of the red light emitting section 10R and thegreen light emitting section 10G and the effect of the resonatorstructure of the blue light emitting section 10B is reduced, and angledependencies of luminance and chromaticity are reduced. Accordingly,light distribution characteristics can be enhanced. In addition, thelight emitting device 1 having high light distribution characteristicsis also preferable for a display device requiring high image quality,and can enhance the productivity of the display device.

FIG. 6 depicts an example of a variation in chromaticity with viewingangle, for a light emitting device according to a comparative example.In the light emitting device according to the comparative example, anelectrode layer on the substrate side is composed of a single layer ofan Al alloy, and an electrode layer on the light extraction side iscomposed of a single layer of an Ag alloy. Further, in the lightemitting device according to the comparative example, a resonancecondition between the electrode layer on the substrate side and thelight emission center is 0 (namely, Na, Nb, Nc=0), whereas a resonancecondition between the electrode layer on the light extraction surfaceside and the light emission center is 1 (namely, Ma, Mb, Mc=1), and thethird reflective interfaces S3R, S3G and S3B and the fourth reflectiveinterfaces S4R, S4G and S4B are not yet formed. In this instance, in thelight emitting device according to the comparative example, secondcavity structures are formed by structures including the firstreflective interfaces S1R, S1G and S1B and the second reflectiveinterfaces S2R, S2G and S2B. Further, in the light emitting deviceaccording to the comparative example, the third reflective interfacesS3R, S3G and S3B and the fourth reflective interfaces S4R, S4G and S4Baccording to the present embodiment are not provided. FIG. 6 depicts theresults when the film thickness t of the electrode layer on the lightextraction surface side is 13 nm, and the results when the filmthickness t on the light extraction surface side is 21 nm, in the lightemitting device according to the comparative example.

FIG. 7 depicts an example of a variation in chromaticity with viewingangle, for the light emitting device according to a comparative example.FIG. 7 depicts the results when the film thickness t of the electrodelayer on the light extraction surface side is 21 nm, Na, Nb and Nc are0, and Ma, Mb and Mc are 1, as well as the results when Ma, Mb and Mcare 0.

FIG. 8 depicts an example of a variation in chromaticity with viewingangle, for the light emitting device 1 according to the embodiment. Inthe light emitting device 1 according to the embodiment, the electrodelayers 12R, 12G and 12B are each composed of a single layer of an Alalloy, whereas the electrode layers 14R, 14G and 14B are each composedof a single layer of an Ag alloy having a film thickness of 18 nm.Further, for the light emitting device 1 according to the embodiment,FIG. 8 depicts the results when Na, Nb and Nc are 0, and Ma, Mb and Mcare 1, as well as the results when Ma, Mb and Mc are 0. Further, in thelight emitting device 1 according to the embodiment, the thirdreflective interfaces S3R, S3G and S3B and the fourth reflectiveinterfaces S4R, S4G and S4B are provided. Furthermore, in the lightemitting device 1 according to the embodiment, the optical path La3 isset in such a manner that the light with a center wavelength λa in thelight emission spectrum of the red light emitting layer 131R is weakenedby the interference between the third reflective interface S3R and thelight emission center OR. The optical path Lb3 is set in such a mannerthat the light with a center wavelength λb in the light emissionspectrum of the green light emitting layer 131G is weakened by theinterference between the third reflective interface S3G and the lightemission center OG. The optical path Lc3 is set in such a manner thatthe light with a center wavelength λc in the light emission spectrum ofthe blue light emitting layer 131B is intensified by the interferencebetween the third reflective interface S3B and the light emission centerOB.

From FIG. 6 it is seen that in the case where the film thickness t ofthe electrode layer on the light extraction surface side is 13 nm, thechromaticity exceeds 0.020, which is one of indexes representing thesuitability of viewing angle dependency, at or around a point where theviewing angle exceeds 50 degrees. In addition, it is seen from FIG. 6that the viewing angle of chromaticity is worsened when the filmthickness t of the electrode layer on the light extraction surface sideis increased from 13 nm to 21 nm. Thus, it is seen that an increase inthe film thickness t of the electrode layer on the light extractionsurface side worsens the viewing angle characteristics of chromaticity.The reason lies in that as the film thickness t of the electrode layeron the light extraction surface side is increased, the resonancecondition becomes stronger, which, together with the influence ofwavelength dispersion of refractive index, leads to a progressivedeviation of viewing angle characteristics on a color basis.

Besides, it is seen from FIG. 7 that a lowering of the order Ma ofinterference is equivalent to a decrease in the film thickness of theelectrode layer on the light extraction surface side.

On the other hand, it is seen from FIG. 8 that, in the light emittingdevice 1 according to the embodiment, viewing angle characteristic isgood, notwithstanding the film thickness of the electrode layer on thelight extraction surface side is as large as 21 nm. In this instance,the resistance value of the electrode layer on the light extractionsurface side in the light emitting device 1 according to the embodimentis 0.62 (=13 nm/21 nm) times the resistance value of the electrode layeron the light extraction surface side in the light emitting device (t=13nm) according to the comparative example of FIG. 6. Therefore, in thelight emitting device 1 according to the embodiment, not only theviewing angle characteristic but also feed performance is good.

From the foregoing, in the present embodiment, in each of the lightemitting sections (the red light emitting section 10R, the green lightemitting section 10G, and the blue light emitting section 10B), the tworeflective interfaces (the third reflective interface S3R, S3G, S3B andthe fourth reflective interface S4R, S4G, S4B) are provided on the outerside of the cathode electrode (the electrode layer 14R, 14G, 14B), and amicrocavity structure with a minimum resonance condition is formed by astructure which includes the first reflective interface S1R, S1G, S1Band the second reflective interface S2R, S2G, S2B and the thirdreflective interface S3R, S3G, S3B and the fourth reflective interfaceS4R, S4G, S4B. This ensures that worsening of the viewing anglecharacteristics of chromaticity can be restrained, even in the casewhere the cathode electrode (the electrode layer 14R, 14G, 14B) on thelight extraction surface SDR, SDG, SDB side is increased in filmthickness.

Further, in the present embodiment, in each of the light emittingsections (the red light emitting section 10R, the green light emittingsection 10G, and the blue light emitting section 10B), the microcavitystructure is configured in such a manner that the first reflectiveinterface S1R, S1G and the second reflective interface S2R, S2Gintensify light in the wavelength band of the light emitted from eachlight emitting layer (the red light emitting layer 131R, the green lightemitting layer 131G), and that the third reflective interface S3R, S3G,S3B and the fourth reflective interface S4R, S4G, S4B weaken light inthe wavelength band of the light emitted from each light emitting layer(the red light emitting layer 131R, the green light emitting layer 131G)and intensify light in the wavelength band of the light emitted from theblue light emitting layer 131B.

This ensures that red light LR which is gentle in the vicinity of a peakis extracted from the light extraction surface SDR in the red lightemitting section 10R, green light LG which is gentle in the vicinity ofa peak is extracted from the light extraction surface SDG in the greenlight emitting section 10G, and blue light LB which has a steep peak isextracted from the light extraction surface SDB in the blue lightemitting section 10B. As a result, angle dependencies of luminance andchromaticity are reduced in the case where the difference between theeffect of the resonator structures of the red light emitting section 10Rand the green light emitting section 10G and the effect of the resonatorstructure of the blue light emitting section 10B is reduced. Therefore,both good feed performance and good viewing angle characteristic ofchromaticity can be realized. In addition, the light emitting device 1having high viewing angle characteristics is preferable also for adisplay device requiring high image quality, and can enhance theproductivity of the display device.

Besides, in the present embodiment, the optical path between the secondreflective interface S2R and the third reflective interface S3R is notmore than the center wavelength λa of the light emitted from the redlight emitting layer 131R. Similarly, the optical path between thesecond reflective interface S2G and the third reflective interface S3Gis not more than the center wavelength λb of the light emitted from thegreen light emitting layer 131G. The optical path between the secondreflective interface S2B and the third reflective interface S3B is notmore than the center wavelength λc of the light emitted from the bluelight emitting layer 131B. As a result, the peak profiles of the spectraof the lights generated in the red light emitting layer 131R, the greenlight emitting layer 131G and the blue light emitting layer 131B can beadjusted, by the actions of the second reflective interfaces S2R, S2Gand S2B and the third reflective interfaces S3R, S3G and S3B and thefourth reflective interfaces S4R, S4G and S4B on the lights generated inthe light emitting layers (131R, 131G and 131B). Therefore, worsening ofviewing angle characteristics of chromaticity can be restrained, even inthe case where the cathode electrodes (the electrode layers 14R, 14G and14B) on the side of the light extraction surfaces SDR, SDG and SDB areincreased in thickness.

In addition, in the present embodiment, the microcavity structure in thered light emitting section 10R is configured such as to satisfy theabove-mentioned expressions (1), (2), (7), (8), (13), (14), (19) and(20). Similarly, the microcavity structure in the green light emittingsection 10G is configured such as to satisfy the above-mentionedexpressions (3), (4), (9), (10), (15), (16), (21) and (22). This ensuresthat red light LR which is gentle in the vicinity of a peak is extractedfrom the light extraction surface SDR in the red light emitting section10R, and green light LG which is gentle in the vicinity of a peak isextracted from the light extraction surface SDG in the green lightemitting section 10G. As a result, sudden variations in luminance andchromaticity with angle can be restrained.

Further, in the present embodiment, the microcavity structure in theblue light emitting section 10B is configured such as to satisfy theabove-mentioned expressions (5), (6), (11), (12), (17), (18), (23) and(24). This ensures that blue light LB which has a steep peak isextracted from the light extraction surface SDB in the blue lightemitting section 10B. Therefore, the difference between the effect ofthe resonator structures of the red light emitting section 10R and thegreen light emitting section 10G and the effect of the resonatorstructure of the blue light emitting section 10B is reduced, and angledependencies of luminance and chromaticity are reduced. Accordingly,light distribution characteristics can be enhanced. In addition, thelight emitting device 1 having high light distribution characteristicsis also preferable for a display device requiring high image quality,and can enhance the productivity of the display device.

In addition, in the present embodiment, the film thicknesses of theelectrode layers 14R, 14G and 14B are not less than 15 nm. This makes itpossible to enhance feed performance without worsening the angledependency of chromaticity. The reason will be described here referringto FIGS. 9 and 10. FIG. 9 depicts an example of a variation in 45-degreechromaticity viewing angle with film thickness of an electrode on thelight extraction surface side in the light emitting device according toa comparative example. FIG. 10 depicts an example of a variation inrelative luminance with film thickness of an electrode on the lightextraction surface side in the light emitting device according to thecomparative example. FIGS. 9 and 10 depict the results obtained by usingthe same light emitting device as the light emitting device used in FIG.6. It is seen from FIG. 9 that in order that the chromaticity is notmore than 0.020, which is one of indexes representing the suitability ofviewing angle dependency, the film thickness of the electrode on thelight extraction surface side should be less than 15 nm. In other words,in the light emitting device according to the comparative example, ithas been extremely difficult, in practice, to set the film thickness ofthe electrode on the light extraction surface side to 15 nm or above. Onthe other hand, in the present embodiment, the angle dependency ofchromaticity is not worsened even in the case where the film thicknessesof the electrode layers 14R, 14G and 14B are 15 nm or above. It is to benoted, however, that, as depicted in FIG. 10, when the film thickness ofthe electrode on the light extraction surface side is greater than 38nm, the luminance is lower than the luminance at the time when the filmthickness of the electrode on the light extraction surface side is 15nm. Therefore, in the present embodiment, also, the film thicknesses ofthe electrode layers 14R, 14G and 14B are set in the range of 15 to 38nm, whereby the angle dependencies of luminance and chromaticity are notworsened.

Besides, in the present embodiment, the substrate 11 is a circuitsubstrate provided with circuits (pixel circuits 18-1) for driving thered light emitting layers 131R, the green light emitting layers 131G andthe blue light emitting layers 131B. Here, the light emitting device 1is a top emission type light emitting device. As a result, the lightsemitted from the red light emitting layers 131R, the green lightemitting layers 131G and the blue light emitting layers 131B are notshielded by the pixel circuits 18-1 in the circuit substrate, and,therefore, a high light extraction efficiency can be obtained.

In addition, in the present embodiment, it is preferable that the redlight emitting layers 131R, the green light emitting layers 131G and theblue light emitting layers 131B are printed layers. Since organic layersundergo a drying step or the like, differences in their thickness on aregion basis are liable to be generated in the organic layers. In otherwords, a film thickness distribution is liable to be generated in theorganic layers. On the other hand, in the present embodiment, since thered light emitting layers 131R, the green light emitting layers 131G andthe blue light emitting layers 131B are printed layers, differences inthe effect of the resonator structure on a light emitting element basisdue to the film thickness distribution in the red light emitting layers131R, the green light emitting layers 131G and the blue light emittinglayers 131B can be adjusted.

2. Modifications

Modifications of the present embodiment will be described below. In thefollowing description, the same components as those in theabove-described embodiment are denoted by the same reference symbols asused above, and descriptions of them will be omitted.

In the above-described embodiment, the electrode layers 14R, 14G and 14Bhave been each configured by using a single metal layer having a filmthickness of not less than 15 nm. In the above embodiment, however, theelectrode layers 14R, 14G and 14B may each include a laminate of aplurality of conducive layers. In the above embodiment, for example, asdepicted in FIG. 11, a laminate 18R may be provided in place of theelectrode layer 14R. Similarly, in the above embodiment, for example, asdepicted in FIG. 11, a laminate 18G may be provided in place of theelectrode layer 14G. Further, in the above embodiment, for example, asdepicted in FIG. 11, a laminate 18B may be provided in place of theelectrode layer 14B.

The laminate 18R is composed, for example, of a laminate including ametal layer 181R, a transparent layer 182R and a metal layer 183R, asillustrated in FIG. 11. The laminate 18G is composed, for example, of alaminate including a metal layer 181G, a transparent layer 182G and ametal layer 183G, as depicted in FIG. 11. The laminate 18B is composed,for example, of a laminate including a metal layer 181B, a transparentlayer 182B and a metal layer 183B, as depicted in FIG. 11.

The metal layers 181R, 181G and 181B are each formed by using a metallicmaterial high in reflectance. The metal layers 181R, 181G and 181B areeach formed, for example, by using any of magnesium (Mg), silver (Ag)and their alloys. The metal layers 181R, 181G and 181B are thicker thanthe metal layers 183R, 183G and 183B. The thicknesses of the metallayers 181R, 181G and 181B are, for example, 5 to 50 nm. With the metallayers 181R, 181G and 181B each formed by use of such a metallicmaterial high in reflectance, the effect of the resonator structures isenhanced, and light extraction efficiency can be enhanced. As a result,it is possible to restrain power consumption and to prolong the usefullives of the red light emitting section 10R, the green light emittingsection 10G and the blue light emitting section 10B.

The transparent layers 182R, 182G and 182B are each formed by using atransparent conductive material. Examples of the transparent conductivematerial used for the transparent layers 182R, 182G and 182B includeITO, and an oxide of indium and zinc (IZO). The thicknesses of thetransparent layers 182R, 182G and 182B are, for example, 30 to 600 nm.The transparent layer 182R is in contact with the metal layers 181R and183R. The transparent layer 182G is in contact with the metal layers181G and 183G. The transparent layer 182B is in contact with the metallayers 181B and 183B.

The metal layers 183R, 183G and 183B are each formed by using a metallicmaterial high in reflectance. Examples of the metallic material used forthe metal layers 183R, 183G and 183B include, for example, magnesium(Mg), silver (Ag) and their alloys. The total thicknesses of the metallayers 181R, 181G and 181B and the metal layers 183R, 183G and 183B are,for example, not less than 15 nm. The thicknesses of the metal layers183R, 183G and 183B are, for example, 5 to 20 nm. The metal layer 183Ris electrically connected to the metal layer 181R through thetransparent layer 182R. The metal layer 183G is electrically connectedto the metal layer 181G through the transparent layer 182G. The metallayer 183B is electrically connected to the metal layer 181B through thetransparent layer 182B.

The resonator structures of the red light emitting section 10R, thegreen light emitting section 10G and the blue light emitting section 10Bwill be described below.

The red light emitting section 10R includes the first reflectiveinterface S1R, the fifth reflective interface SSR, the sixth reflectiveinterface S6R, the third reflective interface S3R, the fourth reflectiveinterface S4R and the light extraction surface SDR in this order fromthe substrate 11 side. In this instance, a microcavity structure isformed by a structure which includes the first reflective interface S1R,the fifth reflective interface SSR, the sixth reflective interface S6R,the third reflective interface S3R and the fourth reflective interfaceS4R. The light emission center OR of the red light emitting layer 131Ris provided between the first reflective interface S1R and the fifthreflective interface S5R. In other words, the red light emitting layer131R is provided between the first reflective interface S1R and thelight extraction surface SDR which are opposed to each other. The fifthreflective interface S5R is an interface between the red organic layer13R and the metal layer 181R. The sixth reflective interface S6R is aninterface between the transparent layer 182R and the metal layer 183R.

The green light emitting section 10G includes the first reflectiveinterface S1G, the fifth reflective interface S5G, the sixth reflectiveinterface S6G, the third reflective interface S3G, the fourth reflectiveinterface S4G and the light extraction surface SDG in this order fromthe substrate 11 side. In this instance, a microcavity structure isformed by a structure which includes the first reflective interface S1G,the fifth reflective interface S5G, the sixth reflective interface S6G,the third reflective interface S3G and the fourth reflective interfaceS4G. The light emission center OG of the green light emitting layer 131Gis provided between the first reflective interface S1G and the fifthreflective interface S5G. In other words, the green light emitting layer131G is provided between the first reflective interface S1G and thelight extraction surface SDG which are opposed to each other. The fifthreflective interface S5G is an interface between the green organic layer13G and the metal layer 181G. The sixth reflective interface S6G is aninterface between the transparent layer 182G and the metal layer 183G.

The blue light emitting section 10B includes the first reflectiveinterface S1B, the fifth reflective interface S5B, the sixth reflectiveinterface S6B, the third reflective interface S3B, the fourth reflectiveinterface S4B and the light extraction surface SDB in this order fromthe substrate 11 side. In this instance, a microcavity structure isformed by a structure which includes the first reflective interface S1B,the fifth reflective interface S5B, the sixth reflective interface S6B,the third reflective interface S3B and the fourth reflective interfaceS4B. The light emission center OB of the blue light emitting layer 131Bis provided between the first reflective interface S1B and the fifthreflective interface S5B. In other words, the blue light emitting layer131B is provided between the first reflective interface S1B and thelight extraction surface SDB which are opposed to each other. The fifthreflective interface S5B is an interface between the blue organic layer13B and the metal layer 181B. The sixth reflective interface S6B is aninterface between the transparent layer 182B and the metal layer 183B.

The fifth reflective interfaces S5R, S5G and S5B and the sixthreflective interfaces S6R, S6G and S6B each include a reflective filmformed by using a metal.

Fifth Reflective Interfaces S5R, S5G and S5B

Let the red organic layer 13R, the green organic layer 13G and the blueorganic layer 13B be each formed by using a material having a refractiveindex of 1.75, and let the metal layers 181R, 181G and 181B be eachformed by using silver (Ag) having a refractive index of 0.13 and anextinction coefficient of 3.96. In this instance, the fifth reflectiveinterface S5R is disposed at a position of an optical path La5 from thelight emission center OR, the fifth reflective interface S5G is disposedat a position of an optical path Lb5 from the light emission center OG,and the fifth reflective interface S5B is disposed at a position of anoptical path Lc5 from the light emission center OB.

The optical path La5 is set in such a manner that the light with acenter wavelength λa in the light emission spectrum of the red lightemitting layer 131R is intensified by interference between the fifthreflective interface S5R and the light emission center OR. The opticalpath Lb5 is set in such a manner that the light with a center wavelengthλb in the light emission spectrum of the green light emitting layer 131Gis intensified by interference between the fifth reflective interfaceS5G and the light emission center OG. The optical path Lc5 is set insuch a manner that the light with a center wavelength λc in the lightemission spectrum of the blue light emitting layer 131B is intensifiedby interference between the fifth reflective interface S5B and the lightemission center OB.

Specifically, the optical paths La5, Lb5 and Lc5 satisfy the followingexpressions (25) to (30).2La5/λa5+φa5/(2π)=Ha  (25)λa−80<λa5<λa+80  (26)2Lb5/λb5+φb5/(2π)=Hb  (27)λb−80<λb5<λb+80  (28)2Lc5/λc5+φc5/(2π)=Hc  (29)λc−80<λc5<λc+80  (30)whereHa, Hb and Hc are each an integer of not less than 0;the unit of λa, λa5, λb, λb5, λc and λc5 is nm;φa5 is the phase change when the light emitted from the red lightemitting layer 131R is reflected by the fifth reflective interface S5R;φb5 is the phase change when the light emitted from the green lightemitting layer 131G is reflected by the fifth reflective interface S5G;φc5 is the phase change when the light emitted from the blue lightemitting layer 131B is reflected by the fifth reflective interface S5B;φa5 is a wavelength satisfying the expression (26);φb5 is a wavelength satisfying the expression (28); andφc5 is a wavelength satisfying the expression (30).φc5, φb5 and φc5 can be determined by a method similar to that for φa1,φb1 and φc1. When the values of Ha, Hb and Hc are high, the so-calledmicrocavity (minute resonator) effect cannot be obtained. Therefore, itis preferable that Ha=0, Hb=0, and Hc=0.

Here, it is presumed that Na=0, Nb=0, Nc=0, Ha=0, Hb=0, and Hc=0. Inthis case, a microcavity structure with a minimum resonance condition isformed by a structure which includes the first reflective interface S1R,the third reflective interface S3R, the fourth reflective interface S4R,the fifth reflective interface S5R and the sixth reflective interfaceS6R. Similarly, a microcavity structure with a minimum resonancecondition is formed by a structure which includes the first reflectiveinterface S1G, the third reflective interface S3G, the fourth reflectiveinterface S4G, the fifth reflective interface S5G and the sixthreflective interface S6G. Further, a microcavity structure with aminimum resonance condition is formed by a structure which includes thefirst reflective interface S1B, the third reflective interface S3B, thefourth reflective interface S4B, the fifth reflective interface S5B andthe sixth reflective interface S6B.

In the case where the optical path La1 satisfies the above-mentionedexpressions (1) and (2) and where the optical path La5 satisfies theabove-mentioned expressions (25) and (26), a peak of transmittance isgenerated at a predetermined wavelength due to an amplifying effect ofthe first reflective interface S1R and the fifth reflective interfaceS5R. In the case where the optical path Lb1 satisfies theabove-mentioned expressions (3) and (4) and where the optical path Lb5satisfies the above-mentioned expressions (27) and (28), a peak oftransmittance is generated at a predetermined wavelength due to anamplifying effect of the first reflective interface S1G and the fifthreflective interface SSG. In the case where the optical path Lc1satisfies the above-mentioned expressions (5) and (6) and where theoptical path Lc5 satisfies the above-mentioned expressions (29) and(30), a peak of transmittance is generated at a predetermined wavelengthdue to an amplifying effect of the first reflective interface S1B andthe fifth reflective interface S5B.

Sixth Reflective Interfaces S6R, S6G and S6B

The optical path La6 is set, for example, in such a manner that thelight with a center wavelength λa in the light emission spectrum of thered light emitting layer 131R is weakened by interference between thesixth reflective interface S6R and the light emission center OR. In thisinstance, the optical path between the fifth reflective interface S5Rand the sixth reflective interface S6R is not more than the centerwavelength λa of the light emitted from the red light emitting layer131R. The optical path Lb6 is set, for example, in such a manner thatthe light with a center wavelength λb in the light emission spectrum ofthe green light emitting layer 131G is weakened by interference betweenthe sixth reflective interface S6G and the light emission center OG. Inthis instance, the optical path between the fifth reflective interfaceS5G and the sixth reflective interface S6G is not more than the centerwavelength λb of the light emitted from the green light emitting layer131G. The optical path Lc6 is set, for example, in such a manner thatthe light with a center wavelength λc in the light emission spectrum ofthe blue light emitting layer 131B is intensified by interferencebetween the sixth reflective interface S6B and the light emission centerOB. In this instance, the optical path between the fifth reflectiveinterface S5B and the sixth reflective interface S6B is not more thanthe center wavelength λc of the light emitted from the blue lightemitting layer 131B.

The optical paths La6, Lb6 and Lc6 satisfy, for example, the followingexpressions (31) to (36).2La6/λa6+φa6/(2π)=Fa+½  (31)λa−150<λa6<λa+150  (32)2Lb6/λb6+φb6/(2π)=Fb+½  (33)λb−150<λb6<λb+150  (34)2Lc6/λc6+φc6/(2π)=Fc  (35)λc−150<λc6<λc+150  (36)whereFa, Fb and Fc are each an integer of not less than 0;the unit of λa, λa6, λb, λb6, λc and λc6 is nm;φa6 is the phase change when the light emitted from the red lightemitting layer 131R is reflected by the sixth reflective interface S6R;φb6 is the phase change when the light emitted from the green lightemitting layer 131G is reflected by the sixth reflective interface S6G;φc6 is the phase change when the light emitted from the blue lightemitting layer 131B is reflected by the sixth reflective interface S6B;λa6 is a wavelength satisfying the expression (32);λb6 is a wavelength satisfying the expression (34); andλc6 is a wavelength satisfying the expression (36).φa6, φb6 and φc6 can be determined by a method similar to that for φa1,φb1 and φc1. In the case where the optical paths La6, Lb6 and Lc6satisfy the above expressions (31) to (36), the light emitting state canbe adjusted on the light emitting section (the red light emittingsection 10R, the green light emitting section 10G, the blue lightemitting section 10B) basis. Thus, by the addition of the reflection onthe sixth reflective interface S6R, the light generated in the red lightemitting layer 131R is weakened, and the half-value width of thespectrum is broadened. In addition, by the addition of the reflectanceon the sixth reflective interface S6G, the light generated in the greenlight emitting layer 131G is weakened, and the half-value width of thespectrum is broadened. By the addition of the reflection on the sixthreflective interface S6B, the light generated in the blue light emittinglayer 131B is intensified, and the half-value width of the spectrum isnarrowed.

Such a light emitting device 1 can be manufactured by forming theelectrode layers 12R, 12G and 12B, the organic layers (the red organiclayer 13R, the green organic layer 13G, and the blue organic layer 13B),the metal layers 181R, 181G and 181B, the transparent layers 182R, 182Gand 182B, the metal layers 183R, 183G and 183B, the transparent layers15R, 15G and 15B, the transparent layers 16R, 16G and 16B and thetransparent layers 17R, 17G and 17B in this order over the substrate 11.The red organic layers 13R, the green organic layers 13G and the blueorganic layers 13B may be formed by a vapor deposition method or may beformed by printing. In other words, the red organic layers 13R, thegreen organic layers 13G and the blue organic layers 13B may be printedlayers. The metal layers 181R, 181G and 181B may be composed of a commonlayer. In this case, the materials and thicknesses of the metal layers181R, 181G and 181B are equal to one another. The transparent layers182R, 182G and 182B may be composed of a common layer. In this case, thematerials and thicknesses of the transparent layers 182R, 182G and 182Bare equal to one another. The metal layers 183R, 183G and 183B may becomposed of a common layer. In this case, the materials and thicknessesof the metal layers 183R, 183G and 183B are equal to one another.

Operation and Effect

In the light emitting device 1 according to this modification, a drivingcurrent is injected into each of the light emitting layers (the redlight emitting layer 131R, the green light emitting layer 131G, and theblue light emitting layer 131B) of the red light emitting section 10R,the green light emitting section 10G and the blue light emitting section10B through the electrode layers 12R, 12G and 12B and the laminates 18R,18G and 18B. As a result, in each light emitting layer, recombination ofholes and electrons occurs, to produce exitons, thereby emitting light.

For example, the light produced in the red organic layer 13R issubjected to multiple reflection between the first reflective interfaceS1R and the third reflective interface S3R, and is extracted from thelight extraction surface SDR. Red light LR is extracted from the lightextraction surface SDR in the red light emitting section 10R. Greenlight LG is extracted from the light extraction surface SDG in the greenlight emitting section 10G, and blue light LB is extracted from thelight extraction surface SDB in the blue light emitting section 10B. Byadditive mixture of the red light LR, the green light LG and the bluelight LB, various colors are expressed.

In this modification, in each of the light emitting sections (the redlight emitting section 10R, the green light emitting section 10G, andthe blue light emitting section 10B), the two reflective interfaces (thethird reflective interface S3R, S3G, S3B and the fourth reflectiveinterface S4R, S4G, S4B) are provided on the outer side of the cathodeelectrode (the laminate 18R, 18G, 18B), and a microcavity structure witha minimum resonance condition is formed by a structure which includesthe first reflective interface S1R, S1G, S1B and the fifth reflectiveinterface S5R, S5G, S5B and the sixth reflective interface S6R, S6G, S6Band the third reflective interface S3R, S3G, S3B and the fourthreflective interface S4R, S4G, S4B. This ensures that worsening ofviewing angle characteristics of chromaticity can be restrained, even inthe case where the metal layers 181R, 181G and 181B and the metal layers183R, 183G and 183B included in the cathode electrodes on the side ofthe light extraction surfaces SDR, SDG and SDB are increased in filmthickness.

Further, in this modification, in each of the light emitting sections(the red light emitting section 10R, the green light emitting section10G, and the blue light emitting section 10B), the microcavity structureis configured in such a manner that the first reflective interface S1R,S1G and the fifth reflective interface S5R, S5G intensify light in thewavelength band of the light emitted from each light emitting layer (thered light emitting layer 131R, the green light emitting layer 131G) andthat the third reflective interface S3R, S3G, S3B and the fourthreflective interface S4R, S4G, S4B weaken light in the wavelength bandof the light emitted from each light emitting layer (the red lightemitting layer 131R, the green light emitting layer 131G) and intensifylight in the wavelength band of the light emitted from the blue lightemitting layer 131B.

This ensures that red light LR which is gentle in the vicinity of a peakis extracted from the light extraction surface SDR in the red lightemitting section 10R, green light LG which is gentle in the vicinity ofa peak is extracted from the light extraction surface SDG in the greenlight emitting section 10G, and blue light LB which has a steep peak isextracted from the light extraction surface SDB in the blue lightemitting section 10B. As a result, angle dependencies of luminance andchromaticity are reduced in the case where the difference between theeffect of the resonator structures of the red light emitting section 10Rand the green light emitting section 10G and the effect of the resonatorstructure of the blue light emitting section 10B is reduced. Therefore,both good feed performance and good viewing angle characteristic ofchromaticity can be realized. In addition, the light emitting device 1having high viewing angle characteristics is preferable also for adisplay device requiring high image quality, and can enhance theproductivity of the display device.

Besides, in this modification, the optical path between the fifthreflective interface S5R and the sixth reflective interface S6R is notmore than the center wavelength λa of the light emitted from the redlight emitting layer 131R. Similarly, the optical path between the fifthreflective interface S5G and the sixth reflective interface S6G is notmore than the center wavelength λb of the light emitted from the greenlight emitting layer 131G. The optical path between the fifth reflectiveinterface S5B and the sixth reflective interface S6B is not more thanthe center wavelength λc of the light emitted from the blue lightemitting layer 131B. As a result, the peak profiles of the spectra ofthe lights generated in the red light emitting layer 131R, the greenlight emitting layer 131G and the blue light emitting layer 131B can beadjusted, by the actions of the fifth reflective interfaces S5R, S5G andS5B and the sixth reflective interfaces S6R, S6G and S6B on the lightsgenerated in the light emitting layers (131R, 131G and 131B). Therefore,worsening of viewing angle characteristics of chromaticity can berestrained, even in the case where the cathode electrodes (theelectrodes 14R, 14G and 14B) on the side of the light extractionsurfaces SDR, SDG and SDB are increased in thickness.

In addition, in this modification, the microcavity structure in the redlight emitting section 10R is configured such as to satisfy theabove-mentioned expressions (1), (2), (25), (26), (31), (32), (19) and(20). Similarly, the microcavity structure in the green light emittingsection 10G is configured such as to satisfy the above-mentionedexpressions (3), (4), (27), (28), (33), (34), (21) and (22). Thisensures that red light LR which is gentle in the vicinity of a peak isextracted from the light extraction surface SDR in the red lightemitting section 10R, and green light LG which is gentle in the vicinityof a peak is extracted from the light extraction surface SDG in thegreen light emitting section 10G. As a result, sudden variations inluminance and chromaticity with angle can be restrained.

Further, in this modification, the microcavity structure in the bluelight emitting section 10B is configured such as to satisfy theabove-mentioned expressions (5), (6), (29), (30), (35), (36), (23) and(24). This ensures that blue light LB which has a steep peak isextracted from the light extraction surface SDB in the blue lightemitting section 10B. Therefore, the difference between the effect ofthe resonator structures of the red light emitting section 10R and thegreen light emitting section 10G and the effect of the resonatorstructure of the blue light emitting section 10B is reduced, and angledependencies of luminance and chromaticity are reduced. Accordingly,light distribution characteristics can be enhanced. In addition, thelight emitting device 1 having high light distribution characteristicsis also preferable for a display device requiring high image quality,and can enhance the productivity of the display device.

In this modification, the total thicknesses of the metal layers 181R,181G and 181B and the metal layers 183R, 183G and 183B are, for example,not less than 15 nm. This makes it possible to enhance feed performancewithout worsening the angle dependency of chromaticity. Besides, in thismodification, like in the above-described embodiment, the totalthicknesses of the metal layers 181R, 181G and 181B and the metal layers183R, 183G and 183B are set in the range of 15 to 38 nm, whereby theangle dependencies of luminance and chromaticity are not worsened.

In addition, in this modification, the substrate 11 is a circuitsubstrate provided with circuits (pixel circuits 18-1) for driving thered light emitting layers 131R, the green light emitting layers 131G andthe blue light emitting layers 131B. Here, the light emitting device 1is a top emission type light emitting device. This ensures that thelights emitted from the red light emitting layers 131R, the green lightemitting layers 131G and the blue light emitting layers 131B are notshielded by the pixel circuits 18-1 in the circuit substrate, and,therefore, a high light extraction efficiency can be obtained.

Besides, in this modification, it is preferable that the red lightemitting layers 131R, the green light emitting layers 131G and the bluelight emitting layers 131B are printed layers. Since organic layersundergo a drying step or the like, differences in their thickness on aregion basis are liable to be generated in the organic layers. In otherwords, a film thickness distribution is liable to be generated in theorganic layers. On the other hand, in the present embodiment, since thered light emitting layers 131R, the green light emitting layers 131G andthe blue light emitting layers 131B are printed layers, differences inthe effect of the resonator structure on a light emitting element basisdue to the film thickness distribution in the red light emitting layers131R, the green light emitting layers 131G and the blue light emittinglayers 131B can be adjusted.

3. Application Examples

Application examples of the light emitting device 1 described in theabove embodiment and the like will be described below.

Application Example A

FIG. 12 depicts a general configuration example of a display device 2which is an application example of the light emitting device 1 accordingto the above-described embodiment and modifications thereof. FIG. 13depicts an example of a circuit configuration of each pixel 18 providedin the display device 2. The display device 2 includes, for example, thelight emitting device 1, a controller 20 and a driver 30. The driver 30is mounted, for example, at an outer edge portion of the light emittingdevice 1. The light emitting device 1 includes a plurality of pixels 18arranged in a matrix pattern. The controller 20 and the driver 30 drivethe light emitting device 1 (the plurality of pixels 18), based on avideo signal Din and a synchronizing signal Tin which are externallyinputted.

Light Emitting Device 1

The light emitting device 1 displays an image based on the video signalDin and the synchronizing signal Tin, which are externally inputted,through active matrix driving of the pixels 18 by the controller 20 andthe driver 30. The light emitting device 1 includes a plurality ofscanning lines WSL extending in a row direction, a plurality of signallines DTL extending in a column direction, a plurality of power supplylines DSL, and the plurality of pixels 18 arranged in the matrixpattern.

The scanning lines WSL are used for selection of each pixel 18, andsupply each pixel 18 with a selection pulse for selecting the pixels 18on the basis of a predetermined unit (for example, pixel row). Thesignal lines DTL are used for supplying each pixel 18 with a signalvoltage Vsig according to the video signal Din, and supply each pixel 18with data pulses including the signal voltage Vsig. The power supplylines DSL are for supplying each pixel 18 with electric power.

The plurality of pixels 18 provided in the light emitting device 1include pixels 18 for emitting red light, pixels 18 for emitting greenlight, and pixels 18 for emitting blue light. Hereinafter, the pixels 18for emitting red light will be referred to as pixels 18R, the pixels 18for emitting green light will be referred to as pixels 11G, and thepixels 18 for emitting blue light will be referred to as pixels 18B. Inthe plurality of pixels 18, the pixels 11R, 11G and 11B constitute adisplay pixel, which is a display unit of color images. Note that eachdisplay pixel may further include, for example, pixels 18 for emittinglight in other color (e.g., white, yellow, or the like). Therefore, theplurality of pixels 18 provided in the light emitting device 1 aredivided into groups as display pixels, each having a predeterminednumber of pixels 18. In each display pixel, the plurality of pixels 18are aligned in a line in a predetermined direction (e.g., rowdirection).

Each signal line DTL is connected to an output end of a horizontalselector 31, which will be described later. For example, one each of theplurality of signal lines DTL is allocated to each pixel column. Eachscanning line WSL is connected to an output end of a light scanner 32,which will be described later. For example, one each of the plurality ofscanning lines WSL is allocated to each pixel row. Each power supplyline DSL is connected to an output end of a power source. For example,one each of the plurality of power supply lines DSL is allocated to eachpixel row.

Each pixel 18 includes the pixel circuit 18-1 and an organicelectroluminescent section 18-2. The organic electroluminescent section18-2 corresponds to the light emitting section (e.g., the red lightemitting section 10R, the green light emitting section 10G, or the bluelight emitting section 10B) according to the above-described embodimentand modifications thereof.

The pixel circuit 18-1 controls light emission and quenching of theorganic electroluminescent section 18-2. The pixel circuit 18-1 has afunction of holding a voltage written into each pixel 18 by writescanning. The pixel circuit 18-1 includes, for example, a drivingtransistor Tr1, a writing transistor Tr2 and a storage capacitor Cs.

The writing transistor Tr2 controls the application of the signalvoltage Vsig corresponding to the video signal Din to a gate of thedriving transistor Tr1. Specifically, the writing transistor Tr2 samplesthe voltage of the signal line DTL, and writes the voltage obtained bythe sampling into the gate of the driving transistor Tr1. The drivingtransistor Tr1 is connected in series with the organicelectroluminescent section 18-2. The driving transistor Tr1 drives theorganic electroluminescent section 18-2. The driving transistor Tr1controls a current flowing through the organic electroluminescentsection 18-2 in accordance with the magnitude of the voltage sampled bythe writing transistor Tr2. The storage capacitor Cs is for holding apredetermined voltage between the gate and a source of the drivingtransistor Tr1. The storage capacitor Cs has a role of keeping constantthe gate-source voltage of the driving transistor Tr1 during apredetermined period. Note that the pixel circuit 18-1 may have acircuit configuration obtained by adding various capacitors andtransistors to the aforementioned 2Tr-1C circuit, or may have a circuitconfiguration different from the aforementioned 2Tr-1C circuitconfiguration.

Each signal line DTL is connected to an output end of the horizontalselector 31, which will be described later, and to a source or a drainof the writing transistor Tr2. Each scanning line WSL is connected to anoutput end of the light scanner 32, which will be described later, andto a gate of the writing transistor Tr2. Each power supply line DSL isconnected to a power supply circuit and to the source or a drain of thedriving transistor Tr1.

The gate of the writing transistor Tr2 is connected to the scanning lineWSL. The source or the drain of the writing transistor Tr2 is connectedto the signal line DTL. That one terminal of the source and the drain ofthe writing transistor Tr2 which is not connected to the signal line DTLis connected to the gate of the driving transistor Tr1. The source orthe drain of the driving transistor Tr1 is connected to the power supplyline DSL. That one terminal of the source and the drain of the drivingtransistor Tr1 which is not connected to the power supply line DSL isconnected to an anode 21 of the organic electroluminescent section 18-2.One end of the storage capacitor Cs is connected to the gate of thedriving transistor Tr1. The other end of the storage capacitor Cs isconnected to that one terminal of the source and the drain of thedriving transistor Tr1 which is on the organic electroluminescentsection 18-2 side.

Driver 30

The driver 30 includes, for example, the horizontal selector 31 and thelight scanner 32. The horizontal selector 31 applies the analog signalvoltage Vsig, inputted from the controller 20, to each signal line DTLin accordance with (synchronously with) an input of a control signal,for example. The light scanner 32 scans the plurality of pixels 18 onthe basis of a predetermined unit.

Controller 20

The controller 20 will be described below. The controller 20 applies,for example, predetermined correction to the digital video signal Dininputted externally, and, based on a video signal obtained thereby,produces the signal voltage Vsig. The controller 20 outputs the producedsignal voltage Vsig to the horizontal selector 31, for example. Thecontroller 20 outputs a control signal to each circuit in the driver 30in accordance with (synchronously with) the synchronizing signal Tininputted externally, for example.

In this application example, the light emitting device 1 is used as adisplay panel for displaying images. By this, even in the case where thelight emitting device 1 is large, it is possible to provide a displaydevice 2 having excellent display quality as well as small angledependencies of luminance and chromaticity.

Application Example B

The display device 2 according to Application Example A described abovecan be used for various types of electronic apparatuses. FIG. 14 depictsa perspective configuration of an electronic apparatus 3 obtained byapplication of the display device 2 according to Application Example Adescribed above. The electronic apparatus 3 is, for example, asheet-shaped personal computer including a display surface 320 at a mainsurface of a housing 310. The electronic apparatus 3 has the displaydevice 2 according to the above-described Application Example A at thedisplay surface 320. The display device 2 according to theabove-described Application Example A is disposed such that a videodisplay surface is directed to the outside. In this application example,the display device 2 according to Application Example A described aboveis provided at the display surface 320; therefore, even in the casewhere the display surface 320 is large in size, it is possible toprovide an electronic apparatus 3 having excellent display quality aswell as small angle dependencies of luminance and chromaticity.

Application Example C

An application example of the light emitting device 1 according to theabove-described embodiment and modifications thereof will be describedbelow. The light emitting device 1 according to the above-describedembodiment and modifications thereof is applicable to light sources ofillumination apparatuses in all fields, such as table or floor typeillumination apparatuses or room illumination apparatus.

FIG. 15 depicts appearance of a room illumination apparatus obtained byapplication of the light emitting device 1 according to theabove-described embodiment and modifications thereof. The illuminationapparatus has, for example, illuminating sections 410 each including thelight emitting device 1 according to the above-described embodiment andmodifications thereof. An appropriate number of the illuminatingsections 410 are arranged at appropriate intervals at a ceiling 420 of abuilding. Note that the illuminating sections 410 can be disposed notonly at the ceiling 420 but also at an arbitrary place such as a wall430 or a floor (not illustrated), according to the use thereof.

In these illumination apparatuses, illumination is conducted by lightfrom the light emitting devices 1 according to the above-describedembodiment and modifications thereof. As a result, it is possible torealize an illumination apparatus having excellent illumination qualityas well as small angle dependencies of luminance and chromaticity.

While the present disclosure has been described above by showing theembodiment, the present disclosure is not to be limited to theembodiment, and various modifications are possible. Note that theeffects described herein are mere examples. The effects of the presentdisclosure are not to be limited to those described herein. The presentdisclosure may have other effects than those described herein. Inaddition, the present disclosure may have the following configurations.

(1)

A light emitting device including:

a plurality of organic electroluminescent sections each including afirst electrode layer, an organic light emitting layer, a secondelectrode layer having a film thickness of not less than 15 nm and areflective layer in this order; and

a light extraction surface from which light emitted from each of theorganic electroluminescent sections through the reflective layer isextracted,

in which the reflective layer includes two reflective interfaces,

in each of the organic electroluminescent sections, a microcavitystructure is formed by a structure including a first reflectiveinterface on the organic light emitting layer side of the firstelectrode layer, a second reflective interface on the organic lightemitting layer side of the second electrode layer, and the tworeflective interfaces included in the reflective layer,

the plurality of organic electroluminescent sections include a pluralityof first organic electroluminescent sections that emit light in a firstwavelength band, and a plurality of second organic electroluminescentsections that emit light in a second wavelength band on a shorterwavelength side than the first wavelength band, and

in each of the first organic electroluminescent sections and each of thesecond organic electroluminescent sections, the microcavity structure isconfigured in such a manner that the first reflective interface and thesecond reflective interface intensify the light in the first wavelengthband and the light in the second wavelength band, and that the tworeflective interfaces included in the reflective layer weaken the lightin the first wavelength band and intensify the light in the secondwavelength band.

(2)

The light emitting device as described in the above paragraph (1),

in which optical paths between the second reflective interface and thetwo reflective interfaces included in the reflective layer are not morethan a center wavelength of the light emitted from the correspondingorganic light emitting layer.

(3)

The light emitting device as described in the above paragraph (1) or(2),

in which the microcavity structure is a microcavity structure with aminimum resonance condition.

(4)

The light emitting device as described in the above paragraph (3),

in which in each of the first organic electroluminescent sections andeach of the second organic electroluminescent sections, the microcavitystructure is configured such as to satisfy the following expressions (A)to (H):2La1/λa1+φa1/(2π)=0  (A)λa−150<λa1<λa+80  (B)2La2/λa2+φa2/(2π)=0  (C)λa−80<λa2<λa+80  (D)2La3/λa3+φa3/(2π)=Ka+½  (E)λa−150<λa3<λa+150  (F)2La4/λa4+φa4/(2π)=Ja+½  (G)λa−150<λa4<λa+150  (H)where

La1 is an optical path between the first reflective interface and alight emission center of the organic light emitting layer of the firstorganic electroluminescent section;

La2 is an optical path between the second reflective interface and thelight emission center of the organic light emitting layer of the firstorganic electroluminescent section;

La3 is an optical path between one reflective interface of the tworeflective interfaces included in the reflective layer and the lightemission center of the organic light emitting layer of the first organicelectroluminescent section;

La4 is an optical path between the other reflective interface of the tworeflective interfaces included in the reflective layer and the lightemission center of the organic light emitting layer of the first organicelectroluminescent section;

φa1 is a phase change when the light emitted from the organic lightemitting layer is reflected by the first reflective interface, in thefirst organic electroluminescent section;

φa2 is a phase change when the light emitted from the organic lightemitting layer is reflected by the second reflective interface, in thefirst organic electroluminescent section;

φa3 is a phase change when the light emitted from the organic lightemitting layer is reflected by the one reflective interface of the tworeflective interfaces included in the reflective layer, in the firstorganic electroluminescent section;

φb4 is a phase change when the light emitted from the organic lightemitting layer is reflected by the other reflective interface of the tworeflective interfaces included in the reflective layer, in the firstorganic electroluminescent section;

λa is a center wavelength in a light emission spectrum of the organiclight emitting layer of the first organic electroluminescent section;

λa1 is a wavelength satisfying the expression (B);

λa2 is a wavelength satisfying the expression (D);

λa3 is a wavelength satisfying the expression (F);

λa4 is a wavelength satisfying the expression (H); and

Ka and Ja are each an integer of not less than 0.

(5)

The light emitting device as described in the above paragraph (4),

in which in each of the first organic electroluminescent sections andeach of the second organic electroluminescent sections, the microcavitystructure is configured such as to satisfy the following expressions (I)to (P):2Lc1/λc1+φc1/(2π)=0  (I)λc−150<λc1<λc+80  (J)2Lc2/λc2+φc2/(2π)=0  (K)λc−80<λc2<λc+80  (L)2Lc3/λc3+φc3/(2π)=Kc  (M)λc−150<λc3<λc+150  (N)2Lc4/λc4+φc4/(2π)=Jc  (O)λc−150<λc4<λc+150  (P)where

Lc1 is an optical path between the first reflective interface and alight emission center of the organic light emitting layer of the secondorganic electroluminescent section;

Lc2 is an optical path between the second reflective interface and thelight emission center of the organic light emitting layer of the secondorganic electroluminescent section;

Lc3 is an optical path between the one reflective interface of the tworeflective interfaces included in the reflective layer and the lightemission center of the organic light emitting layer of the secondorganic electroluminescent section;

Lc4 is an optical path between the other reflective interface of the tworeflective interfaces included in the reflective layer and the lightemission center of the organic light emitting layer of the secondorganic electroluminescent section;

φc1 is a phase change when the light emitted from the organic lightemitting layer is reflected by the first reflective interface, in thesecond organic electroluminescent section;

φc2 is a phase change when the light emitted from the organic lightemitting layer is reflected by the second reflective interface, in thesecond organic electroluminescent section;

φc3 is a phase change when the light emitted from the organic lightemitting layer is reflected by the one reflective interface of the tworeflective interfaces included in the reflective layer, in the secondorganic electroluminescent section;

φc4 is a phase change when the light emitted from the organic lightemitting layer is reflected by the other reflective interface of the tworeflective interfaces included in the reflective layer, in the secondorganic electroluminescent section;

λc is a center wavelength in the light emission spectrum of the organiclight emitting layer of the second organic electroluminescent section;

λc1 is a wavelength satisfying the expression (J);

λc2 is a wavelength satisfying the expression (L);

λc3 is a wavelength satisfying the expression (N);

λc4 is a wavelength satisfying the expression (P); and

Kc and Jc are each an integer of not less than 0.

(6)

The light emitting device as described in any one of the aboveparagraphs (1) to (5),

in which the second electrode layer is configured by using a singlemetal layer having a film thickness of not less than 15 nm.

(7)

The light emitting device as described in any one of the aboveparagraphs (1) to (5),

in which the second electrode layer includes a first metal layer, atransparent conductive layer and a second metal layer in this order fromthe organic light emitting layer side, and

the total thickness of the first metal layer and the second metal layeris not less than 15 nm.

(8)

The light emitting device as described in the above paragraph (7),

in which the first metal layer is thicker than the second metal layer.

(9)

The light emitting device as described in any one of the aboveparagraphs (1) to (8), further including:

a circuit substrate formed with a driving circuit for driving each ofthe organic electroluminescent sections, on a side opposite to the lightextraction surface, in positional relation with each of the organicelectroluminescent sections.

(10)

The light emitting device as described in any one of the aboveparagraphs (1) to (9),

in which the organic light emitting layer is a printed layer.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2018-102520 filed in theJapan Patent Office on May 29, 2018, and Japanese Priority PatentApplication No. 2019-076571 filed in the Japan Patent Office on Apr. 12,2019 the entire content of which is hereby incorporated by reference.

What is claimed is:
 1. A light emitting device, comprising: a pluralityof organic electroluminescent sections each including a first electrodelayer, an organic light emitting layer, a second electrode layer havinga film thickness of not less than 15 nm and a reflective layer in thisorder; and a light extraction surface from which light emitted from eachof the plurality of organic electroluminescent sections through thereflective layer is extracted, wherein the reflective layer includes tworeflective interfaces, in each of the plurality of organicelectroluminescent sections, a microcavity structure is formed by astructure including a first reflective interface on the organic lightemitting layer side of the first electrode layer, a second reflectiveinterface on the organic light emitting layer side of the secondelectrode layer, and the two reflective interfaces included in thereflective layer, the plurality of organic electroluminescent sectionsinclude a plurality of first organic electroluminescent sectionsconfigured to emit light in a first wavelength band, and a plurality ofsecond organic electroluminescent sections configured to emit light in asecond wavelength band on a shorter wavelength side than the firstwavelength band, and in each of the plurality of first organicelectroluminescent sections and each of the plurality of second organicelectroluminescent sections, the microcavity structure is configured insuch a manner that the first reflective interface and the secondreflective interface intensify the light in the first wavelength bandand the light in the second wavelength band, and that the two reflectiveinterfaces included in the reflective layer weaken the light in thefirst wavelength band and intensify the light in the second wavelengthband.
 2. The light emitting device according to claim 1, wherein opticalpaths between the second reflective interface and the two reflectiveinterfaces included in the reflective layer are not more than a centerwavelength of light emitted from a corresponding organic light emittinglayer.
 3. The light emitting device according to claim 1, wherein themicrocavity structure is a microcavity structure with a minimumresonance condition.
 4. The light emitting device according to claim 3,wherein in each of the plurality of first organic electroluminescentsections and each of the plurality of second organic electroluminescentsections, the microcavity structure is configured such as to satisfy thefollowing expressions (A) to (H):2La1/λa1+φa1/(2π)=0  (A)λa−150<λa1<λa+80  (B)2La2/λa2+φa2/(2π)=0  (C)λa−80<λa2<λa+80  (D)2La3/λa3+φa3/(2π)=Ka+½  (E)λa−150<λa3<λa+150  (F)2La4/λa4+φa4/(2π)=Ja+½  (G)λa−150<λa4<λa+150  (H) where La1 is an optical path between the firstreflective interface and a light emission center of the organic lightemitting layer of a first organic electroluminescent section of theplurality of first organic electroluminescent sections; La2 is anoptical path between the second reflective interface and the lightemission center of the organic light emitting layer of the first organicelectroluminescent section; La3 is an optical path between onereflective interface of the two reflective interfaces included in thereflective layer and the light emission center of the organic lightemitting layer of the first organic electroluminescent section; La4 isan optical path between the other reflective interface of the tworeflective interfaces included in the reflective layer and the lightemission center of the organic light emitting layer of the first organicelectroluminescent section; φa1 is a phase change when the light emittedfrom the organic light emitting layer is reflected by the firstreflective interface, in the first organic electroluminescent section;φa2 is a phase change when the light emitted from the organic lightemitting layer is reflected by the second reflective interface, in thefirst organic electroluminescent section; φa3 is a phase change when thelight emitted from the organic light emitting layer is reflected by theone reflective interface of the two reflective interfaces included inthe reflective layer, in the first organic electroluminescent section;φa4 is a phase change when the light emitted from the organic lightemitting layer is reflected by the other reflective interface of the tworeflective interfaces included in the reflective layer, in the firstorganic electroluminescent section; λa is a center wavelength in a lightemission spectrum of the organic light emitting layer of the firstorganic electroluminescent section; λa1 is a wavelength satisfying theexpression (B); λa2 is a wavelength satisfying the expression (D); λa3is a wavelength satisfying the expression (F); λa4 is a wavelengthsatisfying the expression (H); and Ka and Ja are each an integer of notless than
 0. 5. The light emitting device according to claim 4, whereinin each of the plurality of first organic electroluminescent sectionsand each of the plurality of second organic electroluminescent sections,the microcavity structure is configured such as to satisfy the followingexpressions (I) to (P):2Lc1/λc1+φc1/(2π)=0  (I)λc−150<λc1<λc+80  (J)2Lc2/λc2+φc2/(2π)=0  (K)λc−80<λc2<λc+80  (L)2Lc3/λc3+φc3/(2π)=Kc  (M)λc−150<λc3<λc+150  (N)2Lc4/λc4+φc4/(2π)=Jc  (O)λc−150<λc4<λc+150  (P) where Lc1 is an optical path between the firstreflective interface and a light emission center of the organic lightemitting layer of a second organic electroluminescent section of theplurality of second organic electroluminescent sections; Lc2 is anoptical path between the second reflective interface and the lightemission center of the organic light emitting layer of the secondorganic electroluminescent section; Lc3 is an optical path between theone reflective interface of the two reflective interfaces included inthe reflective layer and the light emission center of the organic lightemitting layer of the second organic electroluminescent section; Lc4 isan optical path between the other reflective interface of the tworeflective interfaces included in the reflective layer and the lightemission center of the organic light emitting layer of the secondorganic electroluminescent section; φc1 is a phase change when the lightemitted from the organic light emitting layer is reflected by the firstreflective interface, in the second organic electroluminescent section;φc2 is a phase change when the light emitted from the organic lightemitting layer is reflected by the second reflective interface, in thesecond organic electroluminescent section; φc3 is a phase change whenthe light emitted from the organic light emitting layer is reflected bythe one reflective interface of the two reflective interfaces includedin the reflective layer, in the second organic electroluminescentsection; φc4 is a phase change when the light emitted from the organiclight emitting layer is reflected by the other reflective interface ofthe two reflective interfaces included in the reflective layer, in thesecond organic electroluminescent section; λc is a center wavelength inthe light emission spectrum of the organic light emitting layer of thesecond organic electroluminescent section; λc1 is a wavelengthsatisfying the expression (J); λc2 is a wavelength satisfying theexpression (L); λc3 is a wavelength satisfying the expression (N); λc4is a wavelength satisfying the expression (P); and Kc and Jc are each aninteger of not less than
 0. 6. The light emitting device according toclaim 1, wherein the second electrode layer is configured by using asingle metal layer having a film thickness of not less than 15 nm. 7.The light emitting device according to claim 1, wherein the secondelectrode layer includes a first metal layer, a transparent conductivelayer and a second metal layer in this order from the organic lightemitting layer side, and a total thickness of the first metal layer andthe second metal layer is not less than 15 nm.
 8. The light emittingdevice according to claim 7, wherein the first metal layer is thickerthan the second metal layer.
 9. The light emitting device according toclaim 1, further comprising: a circuit substrate comprising a drivingcircuit configured to drive each of the plurality of organicelectroluminescent sections, on a side opposite to the light extractionsurface, in positional relation with each of the plurality of organicelectroluminescent sections.
 10. The light emitting device according toclaim 1, wherein the organic light emitting layer is a printed layer.